SDN

Software-Defined Networking (SDN) is an emerging architecture that is dynamic, manageable, cost-effective, and adaptable, making it ideal for the high-bandwidth, dynamic nature of today’s applications. This architecture decouples the network control and forwarding functions

 

enabling the network control to become directly programmable and the underlying infrastructure to be abstracted for applications and network services. The OpenFlow® protocol is a foundational element for building SDN solutions. Software-defined networking (SDN) established a foothold in cloud computing, intent-based networking, and network security, with Cisco, VMware, Juniper and others leading the charge. Hardware reigned supreme in the networking world until the emergence of software-defined networking (SDN), a category of technologies that separate the network control plane from the forwarding plane to enable more automated provisioning and policy-based management of network resources.

The goal of SDN is to enable cloud-like computing within a network. This allows network engineers and administrators to respond quickly to changing business requirements via a centralized control console that is abstracted from the physical hardware the network is placed on. SDN encompasses multiple kinds of network technologies designed to make the network more flexible and agile to support the virtualized server and storage infrastructure of the modern data center.

 

 

The SDN Architecture is:

 

DIRECTLY PROGRAMMABLE

Network control is directly programmable because it is decoupled from forwarding functions.

 

AGILE

Abstracting control from forwarding lets administrators dynamically adjust network-wide traffic flow to meet changing needs.

 

CENTRALLY MANAGED

Network intelligence is (logically) centralized in software-based SDN controllers that maintain a global view of the network, which appears to applications and policy engines as a single, logical switch.

 

PROGRAMMATICALLY CONFIGURED

SDN lets network managers configure, manage, secure, and optimize network resources very quickly via dynamic, automated SDN programs, which they can write themselves because the programs do not depend on proprietary software.

 

OPEN STANDARDS-BASED AND VENDOR-NEUTRAL

When implemented through open standards, SDN simplifies network design and operation because instructions are provided by SDN controllers instead of multiple, vendor-specific devices and protocols.

 

How Does SDN Work?

SDN providers offer a wide selection of competing architectures. At its most simple, the software-defined networking method centralizes control of the network by separating the control logic to off-device computer resources. All software-defined network solutions have some version of an SDN controller, as well as southbound and northbound application program interfaces (APIs):

 

Controllers:

 

The “brains” of the network, SDN Controllers offer a centralized view of the overall network, enabling network administrators to dictate to the underlying systems (like switches and routers) how the forwarding plane should handle network traffic, and offering a holistic view of network behavior and loads.

 

Southbound APIs:

 

SDN uses southbound APIs to relay information to the switches and routers “below.” OpenFlow, considered the first standard in SDN, was the original southbound API, and once was considered synonymous with SDN. While popular, it is no longer the only API available on the market, as other companies have released their own proprietary versions of it.

 

Northbound APIs:

 

SDN uses northbound APIs to communicate with the applications and business logic “above.” These help network administrators to shape traffic and deploy services through program instead of by manual configuration.

 

Advantage Of SDN

 

1) Network programmability: SDN enables network behavior to be controlled by the software that resides beyond the networking devices that provide physical connectivity. As a result, network operators can tailor the behavior of their networks to support new services, and even individual customers. By decoupling the hardware from the software, operators can introduce innovative, differentiated new services rapidly—free from the constraints of closed and proprietary platforms.

 

2) Logically centralize intelligence and control: SDN is built on logically centralized network topologies, which enable intelligent control and management of network resources. Traditional network control methods are distributed. Devices function autonomously with limited awareness of the state of the network. With the kind of centralized control an SDN-based network provides, bandwidth management, restoration, security, and policies can be highly intelligent and optimized—and an organization gains a holistic view of the network.

 

3) Abstraction of the network: Services and applications running on SDN technology are abstracted from the underlying technologies and hardware that provide physical connectivity from network control. Applications will interact with the network through APIs, instead of management interfaces tightly coupled to the hardware.

 

4) Openness: SDN architectures usher in a new era of openness—enabling multi-vendor interoperability as well as fostering a vendor-neutral ecosystem. Openness comes from the SDN approach itself. The open APIs support a wide range of applications, including cloud orchestration, OSS/BSS, SaaS, and business-critical networked apps. In addition, intelligent software can control hardware from multiple vendors with open programmatic interfaces like OpenFlow. Finally, from within the SDN, intelligent network services and applications can run within a common software environment.

 

A key advantage of SDN technology is the ability for network operators to write programs that utilize SDN APIs and give applications control over network behavior. SDN allows users to develop network-aware applications, intelligently monitor network conditions, and automatically adapt the network configuration as needed.